In e-commerce marketplaces, one or more sellers publish listings describing items for sale. The listings may include textual descriptions of the item for sale and pictures of the items for sale. The seller may offer the item for a fixed price or may auction the item. In some instances, a seller may post more than one listing to describe a single item for sale or may post the same listing in multiple e-commerce marketplaces. This practice may lead to a situation where the seller has sold a single item to more than one buyer.